[CentOS] mdadm size issues

John R Pierce pierce at hogranch.com
Thu Sep 24 06:30:37 UTC 2009


Nathan Norton wrote:
> Hi,
>
> I am trying to create a 10 drive raid6 array. OS is Centos 5.3 (64 Bit)
>
> All 10 drives are 2T in size.
> ....
> mdadm: size set to 1953511936K
> Continue creating array?
>
> As you  can see mdadm sets the size to 1.9T. Looking around there was this limitation on older versions of mdadm if they are the 32 bit version. I am using the 64 bit most up to date version from Centos. 
>   

a "2TB" drive is approximately 2,000,000,000,000 bytes.     This is 
about 1.8TB if you measure a terabyte as 1024^4 the way software does.


    **2 000 000 000 000 / 1024 = 1 953 125 000 Kilobytes**


    **2 000 000 000 000 / 1024^2  = 1 907 348.63 Megabytes**


    *2 000 000 000 000 / (1 024^3) = 1 862.645 Gigabytes*


    **2 000 000 000 000 / (1 024^4) = 1.819 Terabytes
    **





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